1. Field of the Invention
The invention relates to imaging devices, and more particularly to a light-shielding structure of solid-state imaging devices.
2. Description of the Related Art
Solid-state image devices, for example charge-coupled device (CCD) image sensors or complementary metal-oxide semiconductor (CMOS) image sensors, have been widely used in various image-capturing apparatuses, for example digital still cameras, digital video cameras and the like. In solid-state imaging devices, multiple pixels are arrayed on a semiconductor substrate such as a silicon chip. Each pixel has a photoelectric transducer such as a photodiode, which generates a signal charge by performing photoelectric conversion of incident light received by the photodiode. Signal charges corresponding to photoelectrons generated in the photodiodes are obtained by a CCD-type or a CMOS-type reading circuit.
Solid-state imaging devices are roughly classified into two groups in terms of the direction of light incident on a light receiving unit. One is front-side illuminated (FSI) imaging devices that receive light incident on the front side of a semiconductor substrate on which a wiring layer of the reading circuit is formed. The other is back-side illuminated (BSI) imaging devices that receive light incident on the back side of a semiconductor substrate on which no wiring layer is formed. For imaging a color image, a color filter is provided in the FSI and BSI imaging devices. The FSI and BSI imaging devices usually have a light shielding layer for blocking light between pixels to prevent color mixture.